hey mark,
i have a couple of suggestions. one is to look here and via a search engine for paludaria...these are vivaria which specifically contain large water sections, but also some portion of land. all dart frogs use a bit of land area, especially to feed. getting insects heavy with supplement powders in to the frogs without a land section would be a real challenge. also aggression related fatalities often involve drowning, so without land your otherwise normal aggression might be much more serious.
all of the 'tinc group', which includes auratus and azureus, are primarily terrestrial. they climb more as juveniles, and will continue to climb a bit when adult, but are not truly arboreal.
the thumbs will generally climb more. d. ventrimaculatus are the most commonly recommended beginner frogs of the thumbnails. they are really beautiful and hardier than some thumbs. given the scarcity (not to mention the price) of more delicate thumbs, it's good to start with a more forgiving species while you hone your frogging skills. as far as how they use space, the website nature's web talks about many thumbs, and he uses a keycode system which indicates whether the frogs use more vertical or horizontal space.
http://natures-web.org/.
and saving the best for last, mixing morphs is generally frowned upon in the frog community. there are lots of reasons: different needs of different frogs, aggression levels which can cause fatalities, cross infection with parasites and diseases, and fear of producing hybrids. i think that everyone (myself included) when they encounter darts, want a "community tank" like with aquarium keeping. so this topic comes up a lot, and many of the experienced folks get tired of talking about it. for this reason i highly suggest doin a search on this site for words like "mixed" or "hybrid". you'll turn up lots of info on the topic.
i hope this is helpful and doesn't sound like i'm trying to rain on your parade. i figure that you really care about these animals and want to do things right or else you wouldn't be posting here. the tank you are designing sounds amazing, and i'll look forward to updates on your progress and ensuing questions along the way.
the last piece of advice i'd give is to start culturing your feeder insects well in advance of getting your frogs. it's not hard, but getting the hang of it before your frogs are depending on the results takes a lot of stress out of the learning process.